Optical fibers are often available as cables which include a bare optic fiber at the center, a thin jacket or buffer immediately surrounding the cable, and a thicker outer jacket at the outside. A pair of such cables can be connected together by an arrangement wherein a first cable is mounted within a plug ferrule with the tip of the optic fiber lying at the forward end of the ferrule. The second cable is similarly mounted in a receptacle which receives the plug ferrule so the tips of the optical fibers abut one another. Since the active diameter of the fiber is extremely small, typically 0.002 inch, the radial alignment of the fibers must be held within small tolerances such as a few ten-thousandths of an inch. It is also been found that in typical applications, the ends of the fibers must be aligned within about 1/2.degree., in order to attain acceptable light loss levels. Such precision is currently attained by holding the fibers with precision devices such as jewel bushings, precision balls, or rods. While these methods produce acceptable loss levels, they are relatively costly.
Efforts to produce low cost, one-piece precision ferrules by plastic molding have previously not been successful. Molding has been accomplished by the use of a mold forming a cavity that defines the outside of the ferrule, and a core pin for defining the inside of the ferrule, where the optic cable is received. Only the rearward end of the core pin was held, to thereby provide a passageway for molten plastic to reach the extreme forward end of the cavity. It was found that plastic molding pressures against the core pin, particularly on the male ferrule, resulted in axial displacements ranging from 0.0005 inch to 0.001 inch. Although such movements are very small, they produced angular misalignments in the fiber aligning hole of 1.5.degree. to 3.degree., which is considerably more than the acceptable misalignment angle of about 1/2.degree.. Apparatus that enabled the molding of precision ferrules, wherein the forward fiber-holding cavity portion was precisely concentric with the cylindrical periphery of the ferrule, would enable the production of precision molded connector elements of relatively low cost.